condition mean min max ZT0-3 19.747466666666668 17.599 21.26455 ZT4-7 15.95355 15.95355 15.95355 ZT8-11 19.372700000000002 19.372700000000002 19.372700000000002 ZT12-15 31.138699999999996 30.134999999999998 32.142399999999995 ZT16-19 25.35465 25.35465 25.35465 ZT20-23 26.137050000000002 26.137050000000002 26.137050000000002